The present invention relates to a remote control system.
There has been known to the art a security system having a plurality of security devices interconnected via, for example, a communication control wire (bus) complying with a standard such as RS-485 (EIA-185 Standards). Examples of the security device include a surveillance camera, VTR for recording images picked up by the surveillance camera, frame switcher and the like. Each of the security devices is assigned a specific address for discrimination from the other security devices on the bus. The address setting is done, for example, by means of a DIP switch assembly provided at each security device.
The bus with the security devices connected thereto is connected to a controller for remote control of the security devices or for centralized management of conditions of the security devices. For instance, a remote control of a VTR having address xe2x80x9c1xe2x80x9d is done by transmitting a command containing the address xe2x80x9c1xe2x80x9d of the VTR and a control content such as xe2x80x9cPLAYxe2x80x9d or xe2x80x9cEJECTxe2x80x9d.
In the controller with keys for remotely controlling the security devices, two types of key operations are available which include xe2x80x9csingle key pressxe2x80x9d and xe2x80x9ccontinuous key pressxe2x80x9d. Most remote controls can be done only using information corresponding the single press of any of the keys. However, some controllers are adapted to cause a continuous operation of the security device using information corresponding to a continuously pressed key, such as ZOOM WIDE key and CURSOR key for the surveillance camera. Such keys are referred to as xe2x80x9ccontinuously operable keysxe2x80x9d.
A command corresponding to a continuous press of a continuously operable key may be delivered by, for example, continuous transmission of a key command of the key kept pressed.
Unfortunately, such a command delivery may cause a busy bus condition during the period of the continuous key press. Thus, the controller becomes incapable of controlling other devices or receiving information from other devices.
In view of the foregoing, it is an object of the invention to provide a remote control system capable of transmitting information indicative of the continuous press of the continuously operable key to electronic devices without occupying the bus.
A remote control system according to the invention comprises an electronic device and a controller connected to the electronic device via a bus for remotely controlling the electronic device, the controller provided with keys including a continuously operable key to be kept pressed for causing the electronic device to perform a predetermined operation continuously, the controller having means responsive to a continuous press of the continuously operable key to transmit, to the electronic device, a key command indicative of a type of the pressed key, and means for transmitting a continuous-key-press command to the electronic device at first time intervals of a predetermined length while the key is kept pressed, the electronic device having means which determines the key of the type corresponding to the key command to be kept pressed if, after receipt of the key command, the continuous-key-press command is received at some time point between lapses of the first time period and a second time period longer than the first time period, and then triggers a continuous-key-press control operation associated with the continuous-key-press command, and means which, at each receipt of the continuous-key-press command, determines whether or not the next continuous-key-press command is transmitted within the second time period after receipt of the latest continuous-key-press command and terminates the continuous-key-press control operation if the next continuous-key-press command is not transmitted within the second time period after receipt of the latest continuous-key-press command.
It is preferred that the controller has means responsive to release of the continuously operable key having been kept pressed thereby transmitting a release command indicative of the key release to the electronic device, and that the electronic device has means responsive to the release command to terminate the continuous-key-press control operation.
In a case where two or more controllers are connected to the bus, it is preferred that the electronic device has means which, when the electronic device responds to a continuous-key-press command from one of the controllers to perform a continuous-key-press control operation, nullifies a key command or continuous-key-press command from (any of) the other controller(s)